This disclosure relates to very long endless conveyor belt assemblies which are portable for movement in a direction transverse to their length. The belt assembly is designed for transporting loose, particulate material over long distances in conjunction with other handling equipment. As an example, the conveyor might be used in strip mining operations to remove the soil or overburden, or alternately to mine the desired one. The material might be placed on the conveyor by any type of material handling equipment, such as a dragline bucket, an upright blade or shear, a digging wheel, an auger, etc. The conveyor assembly is designed for use in removing surface material across a wide area with full capability for transverse movement of the conveyor to reposition it as the material is stripped away from the surface of the earth or is moved from large storage piles.
Movable conveyor systems have been used widely, although most move in a direction longitudinally along the length of the belt conveyor. Typical of conveyor systems that are intended to be very long conveyors that are transversely movable are the systems shown in the patent of Stephens, U.S. Pat. No. 2,331,813 and the patent to Becker, U.S. Pat. No. 2,266,673.
Many long conveyors, particularly movable and articulated conveyors, use a series of conveyors cascading from one to another rather than a single elongated belt. An illustration is shown in the Poundstone U.S. Pat. No. 3,003,613. However, the multiplicity of conveyors and motors required for such an apparatus greatly increases the statistical probability of mechanical failure in such a multiple system. The cost of building such a multiple mechanism is substantially greater than the costs encountered when using a single belt.
The use of a single belt is clearly desirable when conveying solid bulk materials over long, straight distances. A difficulty in moving the framework for a long single belt conveyor in a direction transverse to its length is encountered in maintaining the supporting framework for the conveyor in the straight-line configuration essential for proper support and for tracking of the belt. Another problem is torsional movement of the belt. Often terrain is not level along the entire length of the conveyor and the belt will develop a longitudinal twist. Material thus carried on the off-horizontal surface may spill over the side. The apparatus disclosed in this application was designed specifically to meet these problems by the application of automatic steering and alignment controls, and by positively controlling the lateral horizontal orientation of the conveyor working surface relative to angular displacement of its mobile supports.